1. Ac-voltammetry and ac-modulated interfacial voltfluorometry revealed that the slower rate of the transfer of xanthene-type dye anions across the liquid-liuqid interface is ascribed to the transient adsorption of these ions at the interface. Even ions that are considered to have no surface activity can stay some time at the interface, resulting in the slower rate of the interfacial ion transfer. 2. It is demonstrated theoretically that the potential dependent adsorption and partition of ionic surfactants results in the maximum adsorption at the potential around its standard ion-transfer potential. The generality of the conclusion signifies its importance in dealing with various interfacial phenomena in the presence of ioinic surfactants in liquid-liquid two-phase systems. 3. A new criterion of instability of liquid-liquid two-phase systems containing ionic surfactants is proposed. The dependence of the adsorption on the phase-boundary potential can lead to the positive curvature of t
… Morehe electrocapillary curve, which means the negative capacitance of the interface. The interface becomes unstable under this physically unrealistic condition. The spontaneous emulsification, a long-standing riddle in surface chemistry, can be explained by this new concept. 4. The fusion of emulsion particles to the polarized liquid-liquid interface can be monitored electrochemically. The discrete nature of the fusion event is exhibited as a train of current spikes. When the area of the interface is on the order of square centimeter, the fusion takes place as an avalanche, that is, the transfer of many smaller particles triggered by the fusion of a large emulsion particle, whereas a single fusion event is monitored when a micro liquid-liquid interface is employed. 5. A two-phase azo coupling can be quantitatively studied using electrochemical techniques. This reaction is best described as ErCiEr, that is, the reversible ion transfer, a succeeding irreversible chemical reaction in a homogeneous bulk solution phase, and the following back transfer of protons to the aqueous phase. Aryl-azo cations are reduced in the organic phase containing a reductant. The produced aryl-radicals can initiate the radical polymerization at the interface. 6. The mode of the coupling of electron transfer and ion transfer reactions at the liquid-liquid interface has been studied both experimentally and theoretically. In the case of thin-organic-layer covered electrodes dipped in an aqueous solution, the criterion has been quantitatively established for accurately determining the rate of electron tranfer reactions at the liquid-liquid interface. Less